const std = @import("std");
const api = @import("api.zig");
const memory = @import("memory.zig");

// GPU资源类型
export const GpuResourceType = enum(u8) {
    buffer = 1,
    texture = 2,
    shader = 3,
    pipeline = 4,
    command_buffer = 5,
};

// GPU缓冲区描述
export const GpuBufferDesc = struct {
    size: u64,
    usage: u32, // 位掩码，指示缓冲区用途
};

// GPU纹理描述
export const GpuTextureDesc = struct {
    width: u32,
    height: u32,
    format: u32,
    usage: u32,
};

// GPU队列类型
export const GpuQueueType = enum(u8) {
    graphics = 1,
    compute = 2,
    transfer = 3,
};

// GPU资源ID
export const GpuResourceId = u64;

// GPU资源结构体
const GpuResource = struct {
    id: GpuResourceId,
    type: GpuResourceType,
    size: u64,
    address: api.PhysicalAddress,
    usage: u32,
    allocated: bool,
};

// GPU队列结构体
const GpuQueue = struct {
    id: u32,
    type: GpuQueueType,
    capabilities: u32,
};

// GPU管理器
pub const GpuManager = struct {
    allocator: std.mem.Allocator,
    resources: std.ArrayList(GpuResource),
    queues: std.ArrayList(GpuQueue),
    next_resource_id: GpuResourceId = 1,
    initialized: bool = false,

    // 初始化GPU管理器
    pub fn init(allocator: std.mem.Allocator) !GpuManager {
        var manager = GpuManager{
            .allocator = allocator,
            .resources = std.ArrayList(GpuResource).init(allocator),
            .queues = std.ArrayList(GpuQueue).init(allocator),
        };

        // 在实际系统中，这里会初始化GPU硬件
        std.log.info("GPU Manager initialized");

        // 模拟添加一些队列
        try manager.queues.append(GpuQueue{
            .id = 0,
            .type = .graphics,
            .capabilities = 0x01, // 支持图形命令
        });

        try manager.queues.append(GpuQueue{
            .id = 1,
            .type = .compute,
            .capabilities = 0x02, // 支持计算命令
        });

        try manager.queues.append(GpuQueue{
            .id = 2,
            .type = .transfer,
            .capabilities = 0x04, // 支持传输命令
        });

        manager.initialized = true;
        return manager;
    }

    // 分配GPU资源
    pub fn allocateResource(self: *GpuManager, resource_type: GpuResourceType, size: u64, usage: u32) ?GpuResourceId {
        if (!self.initialized) {
            return null;
        }

        // 分配物理内存
        const phys_addr = memory.global_memory_manager.allocatePhysicalMemory(size, 4096) orelse return null;

        // 创建资源
        const resource_id = self.next_resource_id;
        self.next_resource_id += 1;

        const resource = GpuResource{
            .id = resource_id,
            .type = resource_type,
            .size = size,
            .address = phys_addr,
            .usage = usage,
            .allocated = true,
        };

        self.resources.append(resource) catch return null;

        std.log.info("Allocated GPU resource: id={}, type={}, size={}, address=0x{x}",
            .{resource_id, resource_type, size, phys_addr});

        return resource_id;
    }

    // 释放GPU资源
    pub fn freeResource(self: *GpuManager, resource_id: GpuResourceId) bool {
        if (!self.initialized) {
            return false;
        }

        for (self.resources.items, 0..) |*resource, i| {
            if (resource.id == resource_id and resource.allocated) {
                // 释放物理内存
                if (!memory.global_memory_manager.freePhysicalMemory(resource.address, resource.size)) {
                    return false;
                }

                // 移除资源
                resource.allocated = false;

                std.log.info("Freed GPU resource: id={}", .{resource_id});
                return true;
            }
        }

        return false;
    }

    // 获取资源信息
    pub fn getResourceInfo(self: *GpuManager, resource_id: GpuResourceId) ?*GpuResource {
        for (self.resources.items) |*resource| {
            if (resource.id == resource_id and resource.allocated) {
                return resource;
            }
        }
        return null;
    }

    // 提交命令缓冲区到队列
    pub fn submitCommandBuffer(self: *GpuManager, queue_id: u32, command_buffer_id: GpuResourceId) bool {
        if (!self.initialized) {
            return false;
        }

        // 检查队列是否存在
        var queue_found = false;
        for (self.queues.items) |queue| {
            if (queue.id == queue_id) {
                queue_found = true;
                break;
            }
        }

        if (!queue_found) {
            std.log.err("Queue not found: id={}", .{queue_id});
            return false;
        }

        // 检查命令缓冲区是否存在
        const cmd_buffer = self.getResourceInfo(command_buffer_id);
        if (cmd_buffer == null or cmd_buffer.?.type != .command_buffer) {
            std.log.err("Invalid command buffer: id={}", .{command_buffer_id});
            return false;
        }

        std.log.info("Submitted command buffer to queue: cmd_buffer_id={}, queue_id={}",
            .{command_buffer_id, queue_id});

        // 在实际系统中，这里会将命令缓冲区提交给GPU执行
        return true;
    }

    // 创建缓冲区
    pub fn createBuffer(self: *GpuManager, desc: GpuBufferDesc) ?GpuResourceId {
        return self.allocateResource(.buffer, desc.size, desc.usage);
    }

    // 创建纹理
    pub fn createTexture(self: *GpuManager, desc: GpuTextureDesc) ?GpuResourceId {
        // 计算纹理所需的内存大小
        // 这里简化处理，实际需要根据格式和其他属性计算
        const size = desc.width * desc.height * 4; // 假设4字节每像素
        return self.allocateResource(.texture, size, desc.usage);
    }

    // 映射GPU资源到主机内存
    pub fn mapResource(self: *GpuManager, resource_id: GpuResourceId) ?api.VirtualAddress {
        // 注意：在实际系统中，这通常需要DMA或特殊的映射操作
        // 这里简化处理，直接返回物理地址作为虚拟地址
        const resource = self.getResourceInfo(resource_id);
        if (resource == null) {
            return null;
        }

        std.log.info("Mapped GPU resource: id={}, address=0x{x}",
            .{resource_id, resource.?.address});

        return @as(api.VirtualAddress, resource.?.address);
    }

    // 解除资源映射
    pub fn unmapResource(self: *GpuManager, resource_id: GpuResourceId) void {
        // 在实际系统中，这里会执行相应的解除映射操作
        std.log.info("Unmapped GPU resource: id={}", .{resource_id});
    }

    // 清理资源
    pub fn deinit(self: *GpuManager) void {
        // 释放所有资源
        for (self.resources.items) |*resource| {
            if (resource.allocated) {
                memory.global_memory_manager.freePhysicalMemory(resource.address, resource.size);
                resource.allocated = false;
            }
        }

        self.resources.deinit();
        self.queues.deinit();
        std.log.info("GPU Manager deinitialized");
    }
};

// 全局GPU管理器实例
pub var global_gpu_manager: GpuManager = undefined;